Towards New Swedish Recommendations for Cautious Perimeter Blasting

A Swedish table of blast damage depths has, in one form or other, been in use since the late-1970s. Its history and the underlying theory are described. New experimental and theoretical findings that point out a number of shortcomings in the table and the underlying theory are presented and discussed. A revised version of the blast damage table was recently introduced in conjunction with new but incomplete recommendations for cautious perimeter blasting. The new table leaves the difficult task of taking into account factory like decoupling, water in the borehole, the rock properties, type of initiation, charge length and the actual bit diameter to the user. This paper discusses different ways of doing this, based on the experimental findings and a recent formula for the prediction of the lengths of radial cracks behind the half-casts. The material presented in this paper is meant to supplement and extend the new Swedish recommendations for cautious perimeter blasting of tunnels, shafts, pits and road cuts.     

厦门东海域鱼类食物网研究

本文分析了厦门东海域58种鱼类的营养关系.根据对它们的食性分析,并依其食料生物的生态类群,将厦门东海域的鱼类食性类型分为:浮游生物食性、底栖生物食性、游泳动物食性、浮游生物和底栖生物、底栖生物和游泳动物食性等5种.该海域鱼类的营养级可分为4级:杂食性鱼类、低级肉食性鱼类、中级肉食性鱼类和高级肉食性鱼类,其中低级肉食性鱼类占优势,为63.79%.本文还分析了厦门东海域鱼类的食物网及其能量流动途径,并提出合理利用和保护厦门东海域鱼类资源的建议.     

准噶尔盆地复杂地区地层压力预测方法研究及应用

准噶尔盆地地层压力分布复杂,长期以来由于地层压力预测不准,在钻井过程中常出现井壁失稳、卡钻、井壁坍塌、钻井液漏失等工程事故,严重影响了钻井速度.为减少工程复杂问题,准确预测地层压力至关重要.为此,在准噶尔盆地开展了断层相关褶皱理论解释复杂构造、利用地质构造建模指导速度建模,求出每层的层速度和真倾角,再用Terzaghi 理论计算地层孔隙压力,计算结果证实地层压力预测精度显著提高.     

Arsenic accumulation and speciation in plants from different habitats

Understanding As accumulation in plants is necessary in order to alleviate problems with As in the environment and to improve sustainable As phytotechnologies. To find suitable candidates for phytoremediation purposes and to investigate specific accumulation patterns due to growth habitat and plant groups, As accumulation in 124 plant species collected from different habitats and speciation in 6 of these plant species, was determined. The data show that submerged plants have a higher accumulation than emergent and terrestrial plants. The As concentration in terrestrial and emergent plants were correlated with the [As]_soil, while the accumulation factor correlated negatively with [As]_soil. Gymnosperms had a high [As]_shoot:[As]_root ratio. The inorganic As species, arsenate and arsenite were found in plants from all habitats and methylarsonic acid (MMA) in all but one plant species. Arsenate predominated in submerged plants. The results suggest that the habitat and the [As]_soil have a strong influence on the As accumulation in plants and that submerged plants and/or gymnosperms might be suitable for phytoremediation of As.     

Crystal Structure and Chemical Composition of Ludwigite from Vranovac Ore Deposit (Boranja Mountain,Serbia)

The crystal structure of ludwigite from Vranovac ore deposit (Boranja Mt., Serbia) was refined using the X-ray powder diffraction (XRPD) Rietveld method in the space group Pbam to a final RB=7.45% and RF=5.26%. It has the unit cell dimensions of: a=9.2515(2) ?; b=12.3109(2) ?; c=3.03712(7) ?; and V=345.91(1) ?3. The calculated distances and angles are mostly in good agreement with the Mg2+-Fe2+ substitutions across the M(1) and M(3) sites, as well as with the Fe3+-Al3+ replacement in the M(4) site. However, the mean observed M(2)-O distance is considerably shorter than prescribed, due to a slight increase of the Fe3+ content in the M(2) site. Such replacement was compensated by slight increase of the Fe2+ content in the M(4) site, resulting in the (Mg1.48Fe2+0.46Fe3+0.05Mn0.02)2.01(Fe3+0.94Fe2+0.04Al0.02)1.00B1.00O5 composition. The formation temperature was estimated to be about 500–600°C. The influences of the various chemical compositions to the crystallographic parameters, M-O distances, M(3) and M(4) sites shift, distortion parameters and estimated valences, were also studied and compared with other reference samples.     

Dissolved oxygen criteria for freshwater fish in New Zealand: a revised approach

Maintenance of suitable conditions in lowland rivers for both fish passage and resident species is crucial to ensuring the long-term sustainability of fish populations. The dissolved oxygen concentration of water is a key factor controlling habitat quality for fish and a critical measure of stream health. Continued land use intensification and greater exploitation of water resources has contributed towards increasing the frequency and duration of low dissolved oxygen events in lowland rivers and the associated risk of adverse effects on fish communities. Revised guidelines are therefore proposed to support setting of biologically relevant dissolved oxygen limits for the protection of New Zealand freshwater fish communities. These guidelines account for both event magnitude and duration, identify different protection levels based on the risk of negative impacts and are based on current scientific knowledge on the tolerances of New Zealand fish species.     

What Causes Cracks in Rock Blasting?

In blasting, a few or many cracks are driven from the borehole into the rock. But what causes the cracks? The most common theory of breakage consists of two stages; first the shock wave causes radial cracks to form around the hole then the gases penetrate into the cracks, and widen them and make them longer. Another theory presented by Brinkmann suggests that the back damage is primarily controlled by shock and that the gas penetration is the mechanism controlling breakout of the burden. He did his experimental work using blasthole liners. Recent research at SveBeFo has examined this matter further. In a quarry a number of benching holes have been blasted simultaneously. In some of these holes tubular Swellex bolts were inflated and decoupled charges put inside the tubes without stemming. Other holes were identically charged but without the lining. Finally some holes were also stemmed. After blasting the cracks in the remaining rock were studied. There was no difference in crack lengths between holes charged normally (no stemming) and holes where the charges were inside the bolts. On the other hand when stemming was used, the crack lengths increased for some explosives but remained the same for an emulsion explosive. In another set up blasted granite blocks were charged in the same way as above. Then we could also measure the bore hole pressure. The pressure gauge consists of a small carbon resistor inside a steel cylinder. It is called LHM (Location-fixed Hydrodynamic Measuring cup) and is placed at the bottom of the hole. A smaller exit hole from the bottom is drilled for the cables. The paper presents the technique and the results obtained from both the quarry blasting and the blasting of the blocks.     

Bioaccumulation of PCB congeners in marine benthic infauna

Field concentrations of polychlorinated biphenyls (PCBs) were measured in sediment and nine marine soft bottom invertebrate species. Lipid- and organic carbon normalised biota-sediment accumulation factors (BSAFs) were determined for 29 nonplanar and 11 coplanar congeners. To investigate whether the bioaccumulation was in thermodynamic equilibrium with the sediment, the determined BSAFs were compared to theoretically calculated ones to obtain a BSAFdet./BSAFtheor-ratio. Large interspecific variations were found: one suspension feeding and one deposit feeding species of brittle stars (Amphiura filiformis and A. chiajei), and one predatory polychaete (Glycera rouxii) had ratios>1 for congeners with logKow>6.5. In these species there was also a linear relationship between logKow and BSAF, both for coplanar and for planar congeners but with lower values for coplanar ones. For other species the pattern was more scattered. Only the deposit feeding polychaete Melinna cristata had BSAFdet./BSAFtheor-ratios<1 for all congeners. Thus, the interspecific variations in bioaccumulation did not correlate with differences in feeding strategies, but may be caused by differences in biotransformation, and in age and size of the analysed specimens.     

气候变化对拉萨河谷冬小麦主要生育期的影响分析

了解气候变化对冬小麦生育期的影响,可为农业应对气候变化、调整农作物种植结构提供科学依据。本文利用1996—2022年近26 a拉萨冬小麦生育期以及逐日平均气温（T_m）、最高气温（T_max）、最低气温（T_min）、气温日较差（DTR）、相对湿度（RH）、降水量（Pr）、日照时数（S）和≥0 ℃积温（∑T₀）等资料,采用线性倾向估计、Pearson相关系数和优势分析方法等,分析了拉萨河谷冬小麦生育期变化特征以及影响的主导气象因子。结果表明：(1)近26 a拉萨河谷冬小麦营养生长期（Vegetative Growth Period,VGP）、生殖生长期（Reproductive Growth Period,RGP）和全生育期（Whole Growth Period,WGP）的T_m均呈上升趋势,T_min升温率大于T_max的升温率,DTR、RH呈减小趋势,∑T₀、Pr和S趋于增加。(2)冬小麦拔节前各生育期提早,提早率为0.47~6.75 d/10 a;拔节后各生育期推迟,推迟率为3.17~7.03 d/10 a;VGP、WGP延长,RGP缩短。(3)拉萨河谷10月、1月T_min和2月T_m的升高,是冬小麦出苗、分蘖和返青期提前的主要因素,导致冬小麦拔节后生育期推迟的重要因素则是4—5月S增加及6月RH减少。